Synovial fluid acts to lubricate the bearing surfaces of bones and bone-like structures which are held in frictional contact within joints. Synovial fluid lubricates muscles, tendons, cartilage, bones, ligaments, and other biological structures that move within the body relative to each other. The human knee is an example of a joint that uses synovial fluid advantageously to provide for lubrication and friction reduction. Synovial fluid is naturally excreted into the cavity of the joint in a normal healthy knee.
There are publications disclosing the use of propylene glycol and phospholipids in synovial fluid. For example, PCT publication WO 97/22345 to Hills et al. provides a discussion of a method of lubrication of synovial fluid by administering a composition comprising a mixture of phospholipids and propylene glycol. Another publication, PCT publication 89/01777 discloses using phospholipids such as hyaluronic acid in saline solution as a lubricant for joints. Hyaluronic acid compositions may reduce the coefficient of kinetic friction between surfaces in contact with each other, and in particular, load bearing surfaces.
Another publication, EP 0 767 212A1, is directed to a process for producing an aqueous solution of phosphorycholine group bearing polymer. This publication is directed to producing such compositions as starting materials for cosmetics having skin beautifying effects, and as contact lens cleaning agents.
U.S. Pat. No. 5,902,800 to Green et al. describes pharmaceutical compositions containing dextran, and a method for treatment of joint inflammation and pain brought about by arthritis, physical trauma, or infection using such dextran-containing formulations. The method comprises administering a bimodal molecular weight dextran formulation in conjunction with drugs or pharmaceuticals, such as corticocosteroids, anti-inflammatory drugs, and antibiotics to enhance the effect of dextran in relieving pain and inflammation in an inflamed joint.